<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>数据类型</title>
    <script>
        var age = 100;
        console.log(age)
        var price = 25.8;
        console.log(price)
        //var sum = undefined;
        var sum ;
        console.log(sum);
        //null 表示的是空的对象
        var person = null;
        console.log(person);

        var  result = true;
        console.log(result);
        //js 一般我们使用""括起来的就是字符串。
        //var  zhangsan  = "张三";
        var  zhangsan  = '张三';
        console.log(zhangsan);
        //检测数据的类型
        console.log(typeof(zhangsan));
        console.log(typeof zhangsan);

        console.log(typeof 100);
        console.log(typeof null);//object 对象
        console.log(typeof undefined);
        console.log(typeof true);
    </script>
</head>
<body>
<input type="text" onclick="alert('hello')">

</body>
</html>